Electronic apparatus and display control method

ABSTRACT

According to an aspect of the present invention, there is provided an electronic apparatus including: a detection unit configured to detect a start of a reproducing of a motion picture to be displayed on a display unit; a change unit configured to change a refresh rate of the display unit when the start of the reproducing of the motion picture is detected, the refresh rate being changed not by changing an operating frequency of the display unit, the refresh rate being changed by changing a blanking period, the blanking period being a period during which a drawing operation of a screen on the display unit is not performed; and a control unit configured to control the display unit to display the motion picture based on the changed refresh rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/499,675 filed on Jul. 8, 2009, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2008-318977,filed on Dec. 15, 2008, the entire contents of both which areincorporated herein by reference.

BACKGROUND

1. Field

An aspect of the present invention relates to an electronic apparatusand a display control method for changing a refresh rate.

2. Description of the Related Art

Use of notebook type portable computers (hereinafter referred tonotebook PC) has heretofore increased with the advance in computertechnology. Such a notebook PC is equipped with a flat panel displaywhich is subjected to display control of screen information.

Nowadays there is a growing tendency toward use of the notebook PC forviewing motion picture contents as the notebook PC becomes widespread.In NTSC-compliant motion pictures, the motion picture contents are 29.97fps or 59.94 fps. On the other hand, the flat panel display generallyhas a refresh rate of 60 Hz. When motion picture contents of 59.94 fpsare displayed on the flat panel display having a refresh rate of 60 Hz,“tearing” occurs.

Therefore, JP-2006-098765-A proposes a technique of discriminatingbetween a still picture and a motion picture to obtain synchronizationwith the rate of motion picture contents at the time of motion picturereproducing.

However, in JP-2006-098765-A, there is no description about displaytiming at which the rate of the motion picture contents is synchronized.Although it is general that pixel clock is changed for synchronizing therate of the motion picture contents, there is a problem that the screenblinks when such switching is performed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various feature of thepresent invention will now be described with reference to the drawings.The drawings and the associated descriptions are provided to illustrateembodiments of the present invention and not to limit the scope of thepresent invention.

FIG. 1 is an exemplary perspective view showing the external appearanceof a notebook PC 100 according to a first embodiment of the invention.

FIG. 2 is an exemplary block diagram showing the hardware configurationof the notebook PC 100 according to the first embodiment.

FIG. 3 is an exemplary block diagram showing the software configurationof the notebook PC 100 according to the first embodiment.

FIG. 4 is an exemplary table showing a first example of display timingfor display control of an HDTV.

FIG. 5 is an exemplary table showing a second example of display timingfor display control of the HDTV.

FIG. 6 is an exemplary conceptual view showing respective parametersforming display timing for displaying a screen.

FIGS. 7A and 7B are exemplary views showing the concept of changing ahorizontal blanking period.

FIG. 8 is an exemplary table showing a first example of display timingfor display control of a flat panel display.

FIG. 9 is an exemplary table showing a second example of display timingfor display control of the flat panel display.

FIG. 10 is an exemplary flow chart showing a procedure of changing arefresh rate for reproducing of motion picture contents in the notebookPC 100.

DETAILED DESCRIPTION

Various embodiments according to the present invention will be describedhereinafter with reference to the accompanying drawings. In general,according to one embodiment of the present invention, there is providedan electronic apparatus including: a detection unit configured to detecta start of a reproducing of a motion picture to be displayed on adisplay unit; a change unit configured to change a refresh rate of thedisplay unit when the start of the reproducing of the motion picture isdetected, the refresh rate being changed not by changing an operatingfrequency of the display unit, the refresh rate being changed bychanging a blanking period, the blanking period being a period duringwhich a drawing operation of a screen on the display unit is notperformed; and a control unit configured to control the display unit todisplay the motion picture based on the changed refresh rate.

Embodiment of the invention as to an electronic apparatus and a displaycontrol method will be described below in detail with reference toaccompanying drawings. Although a notebook PC is described as theelectronic apparatus according to the embodiment in the followingdescription, the embodiment may be applied to another electronicapparatus.

First Embodiment

FIG. 1 is a perspective view showing the external appearance of anotebook PC 100 according to a first embodiment of the invention. Asshown in FIG. 1, the notebook PC 100 has a housing 101, a keyboard 102provided on the housing 101, and a panel housing 104 rotatably connectedto the housing 101 through a hinge portion 103. The housing 101 has alower casing 101 a, and an upper casing 101 b. A front end portion of anupper surface of the upper casing 101 b forms a palm rest portion 105. Atouch pad 106 is provided substantially in the center of the palm restportion 105. A flat panel display 107 for performing display is providedin a central region of the panel housing 104.

Assume that the refresh rate of the flat panel display 107 built in thenotebook PC 100 is 60 Hz which is equal to that of a general notebookPC. When NTSC-compliant motion picture contents of 29.97 fps or 59.94fps are reproduced, a phenomenon called ‘tearing’ occurs because it isnecessary to display the same picture once per 16-17 seconds inaccordance with a difference in the number of frames displayed for asecond.

Therefore, in the notebook PC 100 according to this embodiment, therefresh rate is seamlessly changed to 59.94 Hz in order to avoid‘tearing’ when motion picture contents of 29.97 fps or 59.94 fps arereproduced on the built-in flat panel display 107 of the notebook PC100. That is, the refresh rate of 59.94 Hz is set to be the same as theframe rate of the original NTSC signal. That is, 59.94 Hz is the mostsuitable refresh rate for reproducing NTSC-compliant motion picturecontents, so that picture quality can be improved. A configuration and aprocessing procedure for changing the refresh rate will be describedlater. In practical operation, the refresh rate may be changed to avalue close to 59.94 Hz.

When reproducing of the motion picture contents is completed, therefresh rate is seamlessly returned from 59.94 Hz to 60 Hz. Thisembodiment will be described on a method of changing the refresh rateseamlessly to display motion picture contents on the flat panel display107.

A display control unit described in this embodiment is effective for theflat panel display in which the refresh rate change is limited in somedegree rather than a CRT in which the refresh rate is easily changed,for example.

First, the hardware configuration of the notebook PC 100 according tothis embodiment will be described. As shown in FIG. 2, the notebook PC100 has a CPU 201, a memory controller hub (MCH) 202, a main storage(memory 203), an I/O controller hub (ICH) 204, a graphics controller(GPU) 205, a BIOS-ROM 206, an auxiliary storage (HDD 207), a flat paneldisplay 107, and an HDMI (High-Definition Multimedia Interface)_I/F 208.The ICH 204 is connected to various devices such as ODD, etc. which arenot shown in FIG. 2. The auxiliary storage is not limited to the HDD 207and any other storage device may be used as the auxiliary storage.

The CPU 201 is a processor for controlling the operation of the notebookPC 100. The CPU 201 executes an operating system (OS) loaded from theHDD 207 to the memory 203. The CPU 201 also executes a system BIOS(Basic Input Output System) stored in the BIOS-ROM 206. The system BIOSis a program for hardware control.

The BIOS-ROM 206 stores not only the system BIOS but also a plurality ofEDID (Extended Display Identification Data) data 221 for display controlof the flat panel display 107. These EDID data 221 are expanded on thememory 203 if necessary. A display mode corresponding to the flat paneldisplay 107 is written in the EDID data 221.

The memory controller hub (MCH) 202 is a bridge device for connecting alocal bus of the CPU 201 and the ICH 204 to each other. The MCH 202 hasa built-in memory controller for access control of the memory 203. TheMCH 202 further has a function of performing communication with thegraphics controller 205 through an AGP (Accelerated Graphics Port) bus,a PCI express-based serial bus, etc.

The graphics controller 205 is a display controller for controlling theflat panel display 107. The graphics controller 205 is a displaycontroller for controlling the flat panel display 107 used as a displaymonitor of the notebook PC 100. The graphics controller 205 generates adisplay signal in accordance with a request issued from the OS or anapplication program and transfers the display signal to the flat paneldisplay 107.

The graphics controller 205 may perform display control of an HDTV 205.In this case, the graphics controller 205 generates a display signal inaccordance with a request issued from the OS or an application programand transfers the display signal to the HDTV 250 in the same manner asdescribed above.

The graphics controller 205 has a built-in LVDS_Tx (Low VoltageDifferential Signaling Transmitter) 231. The LVDS_Tx 231 has a PLLcircuit 232, and a display timing control circuit 233. The LVDS_Tx 231is connected to the flat panel display 107. The LVDS_Tx 231 generates adisplay signal for the flat panel display 107.

The PLL circuit 232 can generate any pixel clock (operating frequency).When, for example, the PLL circuit operates at 68.5 MHz, the LVDS_Tx 231outputs a signal at 68.5 MHz to the HDTV 250 or the flat panel display107. When a request is given to the PLL circuit 232 to change theoperating frequency, the PLL circuit 232 can change the operatingfrequency of the LVDS_Tx 231.

The display timing control circuit 233 generates a display signal inaccordance with display timing information designated by a displaydriver 303 which will be described later. Incidentally, the displaytiming information is held as EDID data 221 in the BIOS-ROM 206 inadvance.

The graphics controller 205 further has the HDMI_I/F 208. The notebookPC 100 is connected to the HDTV (High Definition Television) 250 throughthe HDMI_I/F 208. Consequently, the notebook PC 100 can display screendata on the HDTV 250.

The memory 203 holds the display timing information 212 and the displaydriver 211 based on processing in the system BIOS and the OS after thenotebook PC 100 is booted up. The display driver 211 is a program readfrom the HDD 207 under the control of the OS.

The display timing information 212 is information which is read from theEDID data 221 of the BIOS-ROM 206 and expanded on the memory 203 inorder to set the display timing of the flat panel display 107. Thedisplay timing information 212 is also information which is read fromthe HDTV 250 and expanded on the memory 203 in order to perform timingcontrol of the HDTV 250 connected through the HDMI_I/F 208.

The I/O controller hub (ICH) 204 controls respective devices on an LPC(Low Pin Count) bus and respective devices connected to a PCI(Peripheral Component Interconnect) bus. The ICH 204 has a built-in IDE(Integrated Drive Electronics) controller for controlling the HDD 207.

FIG. 3 is a block diagram showing the software configuration of thenotebook PC 100 according to this embodiment. As shown in FIG. 3, thenotebook PC 100 has a system BIOS 301, an OS 302, a display driver 303,and a motion picture reproducing application 304. The system BIOS 301controls hardware devices such as the HDD 207, the HDMI_I/F 208 and theflat panel display 107.

The system BIOS 301 has EDID data 221 and controls hardware inaccordance with an instruction from software such as the OS 302.

The EDID data 221 are EDID data for setting the display timing of theflat panel display 107.

The OS 302 performs execution of software (such as the motion picturereproducing application 304 and the display driver 303) and provision ofhardware resources to the executed software.

The motion picture reproducing application 304 performs reproducing ofmotion picture contents. The motion picture contents may be read into astorage device such as the HDD 207 or into an external device connectedthrough a network. The motion picture reproducing application 304 may bea dedicated application or may be a browser or the like.

The display driver 303 has an EDID reading portion 311, a display timinginformation hold portion 312, a detection portion 313, a change portion314, a refresh rate hold portion 315, and a display control portion 316.

The EDID reading portion 311 reads EDID data necessary for displaycontrol of the flat panel display 107, from the system BIOS 301. Then,display timing information is created from the read EDID data andexpanded on the memory 203.

The EDID reading portion 311 reads EDID data necessary for displaycontrol of the HDTV 250, from the HDTV 250. Then, display timinginformation is created from the read EDID data and expanded on thememory 203.

The display timing information hold portion 312 is present on the memory203 and holds the display timing information expanded on the memory 203by the EDID reading portion 311.

Although the notebook PC 100 and the HDTV 250 are connected to eachother by an HDMI cable, a signal is required to be output at a frequencystandardized in order to keep connectivity. For example, display timingfor 1920×1080 called “full HD resolution” is defined as shown in FIGS. 4and 5. FIG. 4 shows display timing information at the refresh rate of 60Hz. FIG. 5 shows display timing information at the refresh rate of 59.94Hz. First, respective parameters used in display timing information forthe HDTV 250 will be described.

As shown in FIGS. 4 and 5, “Pixel Clock”, “H Total”, “H Active”, “HBlank”, “H sync”, “V Total”, “V Active”, “V Blank” and “V sync” are heldin display timing information while related to one another.

“Pixel Clock” indicating an operating frequency is defined as the numberof pixels drawn for a second. When, for example, the pixel clock is 68.9MHz, it is possible to draw 68900000 pixels per second.

“H Total” is a time period necessary for one horizontal line. “H Total”is equal to the sum of “H Active” and “H Blank”. “H Active” (horizontalactive period) shows a time period (the number of pixels) in which apicture corresponding to one horizontal line is drawn. “H Blank”(horizontal blanking period) shows a time period (the number of pixels)of blanking (non-displaying) in one horizontal line.

“H sync” (horizontal frequency) is defined as the number of (horizontal)lines drawn for a second.

Specifically, the following equation (1) stands up.

H sync=Pixel Clock/(H Total)   (1)

“V Total” is a time period necessary for drawing one screen. “V Total”is equal to the sum of “V Active” and “V Blank”. “V Active” (verticalactive period) shows a time period (the number of (horizontal) lines) inwhich a picture corresponding to one (vertical) screen is drawn. “VBlank” (vertical blanking period) shows a time period (the number of(horizontal) lines) of blanking (non-displaying) in one (vertical)screen.

“V sync” (vertical frequency) shows the number of screens drawn for asecond. In other words, “V sync” (vertical frequency) means a refreshrate.

Specifically, the following equation (2) stands up.

V sync=H sync/(V Total)   (2)

The relationship between these parameters “H Active” (horizontal activeperiod), “H Blank” (horizontal blanking period), “V Active” (verticalactive period) and “V Blank” (vertical blanking period) will bedescribed. FIG. 6 is a conceptual view showing these parameters. Asshown in FIG. 6, the horizontal active period 601 is a time period (thenumber of pixels) for drawing one horizontal line on the flat paneldisplay 107. When, for example, the resolution is 1920×1080, thehorizontal active period 601 is fixed to 1920 pixels. On the other hand,the horizontal blanking period 602 is a time period for makingpreparations for drawing the next horizontal line. The horizontalblanking period 602 can be changed in some degree if necessary.

The vertical active period 603 is a time period (the number of lines)for drawing one screen on the flat panel display 107. When, for example,the resolution is 1920×1080, the vertical active period 603 is fixed to1080 lines. On the other hand, the vertical blanking period 604 is atime period for making preparations for drawing the next screen. Thevertical blanking period 604 can be changed in some degree if necessary.

Both display timings shown in FIGS. 4 and 5 are display timinginformation for a resolution of 1920×1080 but different in parameterssuch as pixel clock, refresh rate, etc. Specifically, differentparameters are “Pixel Clock”, “H sync” and “V sync”.

Strictly speaking, “V sync” in FIG. 5 is not equal to 59.94 Hz. Thismeans that the reproducing timing of NTSC motion picture contents is notexactly equal to the timing of the refresh rate when the NTSC motionpicture contents are reproduced at 29.970029 . . . (59.9400599400 . . ./2) fps.

Incidentally, the difference between the two refresh rates 59.94 Hz and60 Hz in the HDTV 250 is caused by the operating frequency “PixelClock”. When the refresh rate is 60 Hz, the pixel clock is set at 148.50MHz. When the refresh rate is 59.94 Hz, the pixel clock is set at 148.35MHz. These values cannot be changed because these values arestandardized.

If the operating frequency “Pixel Clock” is changed, the screen appearsblinking because the display output signal must be stopped.Consequently, there arises a problem that the user becomes aware ofchange of the refresh rate. If the refresh rate is changed withoutchanging “Pixel Clock”, display control can be performed without user'sawareness of change of the refresh rate.

In the embodiment, the flat panel display 107 need not conform to theaforementioned definition because the flat panel display 107 is notconnected by the HDMI cable but built in the notebook PC 100. That is,display timing can be set freely within the specification of the flatpanel display 107 because the connection between the graphics controller205 and the built-in flat panel display 107 is closed inside thenotebook PC 100. Therefore, in the notebook PC 100 according to thisembodiment, display timing is determined at the time of design anddevelopment so that the graphics controller 205 can perform displaycontrol of the flat panel display 107 at the display timing.

Therefore, in this embodiment, the refresh rate is changed by changingthe blanking period without changing “Pixel Clock”. Referring back toFIG. 3, respective configurations of the notebook PC 100 will bedescribed specifically as follows.

The detection portion 313 detects start of reproducing of motion picturecontents displayed on the flat panel display 107. The detection portion313 further detects suspension of reproducing of the motion picturecontents displayed on the flat panel display 107. The refresh rate ischanged in accordance with a result of the detection. For example, thedetection portion 313 may detect notice of start of reproducing ofmotion picture contents from the motion picture reproducing application304 to thereby detect start of reproducing of the motion picturecontents.

With respect to the motion picture contents start of reproducing ofwhich is detected by the detection portion 313 according to thisembodiment, either 29.97 fps or 59.94 fps can be detected. When themotion picture contents are detected, the change portion 314 changes therefresh rate to 59.94 Hz.

When the detection portion 313 detects start of reproducing of motionpicture contents, the change portion 314 changes only the blankingperiod (horizontal blanking period or vertical blanking period) to agiven value (59.94 Hz in this embodiment) determined for reproducing ofmotion picture contents in advance without changing the operatingfrequency. The change portion 314 changes the refresh rate by changingonly the blanking period. On this occasion, the change portion 314registers the previous set value (before change) in the refresh ratehold portion 315.

That is, in the notebook PC 100 according to this embodiment, thevertical active period and the horizontal active period are not changedbecause the resolution is not changed when the refresh rate is changedfrom 60 Hz to 59.94 Hz without changing the operating frequency “PixelClock”. The refresh rate is changed while the aforementioned equations(1) and (2) are satisfied in consideration of this situation.

Therefore, in the notebook PC 100 according to this embodiment, only theblanking period (the horizontal blanking period and the verticalblanking period) is changed to thereby change the refresh rate.

When the detection portion 313 detects suspension of reproducing of themotion picture contents, the change portion 314 changes the blankingperiod to the previous blanking period (before the motion picturereproducing) held in the refresh rate hold portion 315. In thisembodiment, the change portion 314 changes the horizontal blankingperiod to thereby change the refresh rate.

FIGS. 7A and 7B are explanatory views showing the concept of changingthe horizontal blanking period. As shown in FIGS. 7A and 7B, in thisembodiment, the change portion 314 changes the horizontal blankingperiod so that the refresh rate can be seamlessly changed between 59.94Hz and 60 Hz.

As shown in FIGS. 7A and 7B, in this embodiment, the horizontal blankingperiod is elongated to change the refresh rate from 60 Hz to 59.94 Hz.Consequently, “H Total” becomes long, so that the refresh rate can beshortened based on the equations (1) and (2).

FIGS. 8 and 9 are tables showing examples of display timing informationfor display control of the flat panel display 107. Respective parameternames are the same as in FIGS. 4 and 5 and description thereof will beomitted.

In both FIGS. 8 and 9, “Pixel Clock” is set at 135 MHz. At 60 Hz shownin FIG. 8, the horizontal blanking period “H Blank” is set at 80. At59.94 Hz shown in FIG. 9, the horizontal blanking period “H Blank” isset at 82.

Consequently, “H Total” is 2000 at 60 Hz and 2002 at 59.94 Hz. That is,the ratio of “H Total” at 60 Hz to “H Total” at 59.94 Hz is 1000:1001.From the viewpoint of these parameters and “Pixel Clock” of 135 MHz, therefresh rate can be changed between 60 Hz and 59.94 Hz without changing“Pixel Clock”.

In this manner, in this embodiment, values of respective parameters ofdisplay timing information are set so that values of “H Total” atdisplay timings 60 Hz and 59.94 Hz satisfy the aforementioned values(ratio). Although the case where the resolution is 1920×1080 has beendescribed, the embodiment can be applied to another resolution so thatthe blanking period can be likewise adjusted to change the refresh ratewithout changing “Pixel Clock”.

Because only the blanking period is changed in this manner, it ispossible to change the refresh rate without user's awareness.

In this embodiment, after the value of the horizontal blanking period isset so that “H Total” becomes an integral multiple of 1000, otherdisplay timing parameters (such as “Pixel Clock”) are adjusted to setthe refresh rate at 60 Hz. EDID data 221 for creating such displaytiming information are stored in the BIOS-ROM in advance. The EDIDreading portion 311 reads these EDID data 221 as necessary.

Change of display timing including the refresh rate by the changeportion 314 is performed within the horizontal or vertical blankingperiod.

When the detection portion 313 detects motion picture reproducing, thechange portion 314 increases only the value of the horizontal blankingperiod to an integral multiple of “H Total” so that the refresh rate canbe set at 59.94 Hz.

The refresh rate hold portion 315 saves the previous display timinginformation including the blanking period before the display timinginformation is changed by the change portion 314. When the detectionportion 313 detects suspension of reproducing of the motion picturecontents, the change portion 314 reads the saved display timinginformation and changes the display timing information to the originaldisplay timing information.

The display control portion 316 performs display control of the flatpanel display 107. In this embodiment, the display control portion 316controls the flat panel display 107 based on the set display timinginformation.

When the detection portion 313 detects reproducing of motion picturecontents and the change portion 314 changes the refresh rate, thedisplay control portion 316 performs display control of the flat paneldisplay 107 at the changed refresh rate. In this manner, the refreshrate can be changed from 60 Hz to 59.94 Hz without user's awareness.

Although the notebook PC 100 according to this embodiment has beendescribed on the case where NTSC motion picture contents are used at29.97 fps or 59.94 fps, the motion picture data is not limited theretoand the refresh rate can be changed by changing the blanking period inaccordance with the number of frames displayed for a second in themotion picture data. Because the refresh rate can be changed by changingthe blacking period in this manner, display timing can be changedseamlessly.

The refresh rate of the HDTV 250 cannot be made coincident with thenumber of frames displayed for a second in the motion picture contentsbecause the refresh rate of the HDTV 250 is standardized. On thecontrary, the flat panel display 107 of the notebook PC 100 according tothis embodiment can be controlled to be displayed at a refresh rate of59.94 Hz perfectly coincident with 59.94 fps or twice as much as 29.97fps of NTSC-compliant motion picture contents, so that ‘tearing’ can besuppressed.

A procedure of changing the refresh rate for reproducing of motionpicture contents in the notebook PC 100 will be described next. FIG. 10is a flow chart showing the processing procedure in the notebook PC 100.

First, the detection portion 313 detects start of reproducing of motionpicture contents by the motion picture reproducing application 304 (stepS1001).

Then, the change portion 314 acquires display timing informationincluding the refresh rate currently used for display control (stepS1002). Incidentally, the refresh rate is generally set at 60 Hz beforethe start of reproducing of the motion picture contents.

Then, the change portion 314 determines whether the acquired refreshrate is 59.94 Hz or not (step S1003). When the refresh rate is 59.94 Hz(Yes in the step S1003), this routine is terminated without anyprocessing.

On the other hand, when the refresh rate is determined to be not 59.94Hz (No in the step S1003), the change portion 314 saves display timinginformation including the current refresh rate in the refresh rate holdportion 315 (step S1004).

Then, the change portion 314 changes the horizontal blanking period tothereby change the refresh rate to 59.94 Hz (step S1005).

Then, the display control portion 316 performs display control of theflat panel display 107 at the refresh rate changed (based on thehorizontal blanking period) (step S1006).

Then, the detection portion 313 detects suspension of reproducing of themotion picture contents (step S1007). Then, the change portion 314 readsthe display timing information including the refresh rate held in therefresh rate hold portion 315 and brings the display timing informationback to the original display timing information (step S1008). The changeof the refresh rate is performed by changing the blanking period.

Then, the display control portion 316 performs display control at thebrought-back display timing including the refresh rate (step S1009).

Although this embodiment has been described on the case where thedisplay control is performed by the display driver 303, any program maybe used if the program can perform display control.

Although the notebook PC 100 according to this embodiment has beendescribed on the case where the horizontal blanking period is changed,the vertical blanking period may be changed. Although this embodimenthas been described on the case where the refresh rate is changed from 60Hz to 59.94 Hz, the embodiment is not limited thereto but may be appliedto any case if the refresh rate can be changed in accordance with thenumber of frames per second of motion picture data.

Although this embodiment has been described on display timing at aresolution of 1920×1080, the resolution is not limited if the refreshrate can be changed by changing the blanking period without changing theoperating frequency “Pixel Clock” as described above.

In the notebook PC 100 according to this embodiment, the refresh rategenerally set at 60 Hz is changed to 59.94 Hz only when NTSC-compliantmotion picture contents are reproduced. Consequently, ‘tearing’ can besuppressed.

The horizontal blanking period is changed so that the refresh rate canbe seamlessly changed between 59.94 Hz and 60 Hz when the reproducing ofmotion pictures is started or suspended without user's awareness.

In the notebook PC 100 according to this embodiment, ‘tearing’ can besuppressed because the refresh rate after changing the horizontalblanking period by the change portion 314 is 59.94 Hz which iscoincident with 59.94 fps or twice as much as 29.97 fps ofNTSC-compliant motion picture contents. In this embodiment, picturequality is improved more greatly compared with the case where ‘tearing’cannot be suppressed completely because, for example, the refresh ratefor a resolution of 1920×1080 according to the industry standard is nearto 59.94 Hz but strictly not equal to 59.94 Hz as described above.

The invention is not limited to the embodiment and may be modifiedvariously as follows by way of example.

Modification 1

The first embodiment has been described on the case where the refreshrate of the built-in flat panel display 107 of the notebook PC 100 ischanged. However, the invention is not limited to the built-in flatpanel display 107 of the notebook PC 100 but can be applied to anexternal monitor.

As an example for applying the invention to such an external monitor, itmay be conceived that a vendor who produces the external monitorprovides the external monitor supporting the aforementioned displaytiming.

That is, any external monitor having a function of changing the refreshrate by changing the aforementioned blanking period can be used. Forexample, the external monitor may be a CRT. Any connection method suchas DVI, DisplayPort, or HDMI is conceivable as the connection method.

The display driver 303 executed in the notebook PC 100 according to thisembodiment is provided in the form of an installable or executable filerecorded on a computer-readable recording medium such as a CD-ROM, aflexible disk (FD), a CD-R or a DVD (Digital Versatile Disk).

Alternatively, the display driver 303 executed in the notebook PC 100according to this embodiment may be provided in such a manner that thedisplay driver 303 is stored on a computer connected to a network suchas the Internet and downloaded from the computer via the network. Inaddition, the display driver 303 executed in the notebook PC 100according to this embodiment may be provided or distributed via anetwork such as the Internet.

Alternatively, the display driver 303 may be provided from an ROM or thelike in which the display driver 303 is incorporated in advance.

The display driver 303 is formed as a module including the respectiveportions (the EDID reading portion, the detection portion, the changeportion and the display control portion). With respect to actualhardware, the CPU 201 reads the display driver 303 from theaforementioned recording medium and executes the display driver 303 tothereby load the respective portions on the memory 203 so that the EDIDreading portion, the detection portion, the change portion and thedisplay control portion are created on the memory 203.

According to an aspect of the invention, the refresh rate can be changedwithout user's awareness.

1. An electronic apparatus comprising: a display; a display controllerconfigured to control the display; and a refresh rate controllerconfigured to seamlessly change a refresh rate of the display from afirst frequency to a second frequency lower than the first frequency byincreasing a horizontal blanking period in such a manner that a firstratio of a sum of the horizontal blanking period and a horizontal activeperiod before the change of the refresh rate to the sum after the changeof the refresh rate corresponds to a second ratio of the secondfrequency to the first frequency, the horizontal blanking period being aperiod from an end of a drawing operation of a horizontal line on thedisplay until a beginning of the drawing operation of the nexthorizontal line, the horizontal active period being a period of thedrawing operation of the horizontal line; and wherein the displaycontroller is configured to control the display based on the refreshrate.
 2. The apparatus of claim 1, wherein the refresh rate controlleris not configured to change an operation frequency in controlling thedisplay.
 3. The apparatus of claim 1, wherein the refresh ratecontroller is configured to increase the horizontal blanking periodthereby causing the first ratio a product of the second ratio and afirst number.
 4. An electronic apparatus comprising: a display; adisplay controller configured to control the display; and a refresh ratecontroller configured to seamlessly change a refresh rate of the displayfrom a first frequency to a second frequency higher than the firstfrequency by decreasing a horizontal blanking period in such a mannerthat a first ratio of a sum of the horizontal blanking period and ahorizontal active period before the change of the refresh rate to thesum after the change of the refresh rate corresponds to a ratio of thesecond frequency to the first frequency, the horizontal blanking periodbeing a period from an end of a drawing operation of a horizontal lineon the display until a beginning of the drawing operation of the nexthorizontal line, the horizontal active period being a period of thedrawing operation of the horizontal line; and wherein the displaycontroller is configured to control the display based on the refreshrate.
 5. The apparatus of claim 4, wherein the refresh rate controlleris not configured to change an operation frequency in controlling thedisplay.
 6. A display control method comprising: seamlessly changing arefresh rate of a display from a first frequency to a second frequencylower than the first frequency by increasing a horizontal blankingperiod in such a manner that a ratio of a sum of the horizontal blankingperiod and a horizontal active period before the change of the refreshrate to the sum after the change of the refresh rate corresponds to aratio of the second frequency to the first frequency, the horizontalblanking period being a period from an end of a drawing operation of ahorizontal line on the display until a beginning of the drawingoperation of the next horizontal line, the horizontal active periodbeing a period of the drawing operation of the horizontal line; andcontrolling the display based on the refresh rate.